FTDI has just released a new driver, pushed by Microsoft in a recent Windows update, that will render counterfeit USB-Serial chips non-functional.
This driver changes the data on the chip to have a product ID of 0 (invalid), so once it has been plugged into a Windows box with the new driver,
it won't work even if you restore the old driver.
This happens with many of the "clone" or "fake" FTDI chips found on the cheap eBay/Alibaba usb-serial, usb-rs485, arduino clones, et al. So if a device was working and dies after this Windows update, it's the driver that's causing it.
For more info, and some workarounds, look at
You are not allowed to view links.
Register or
LoginYou are not allowed to view links.
Register or
Login/mike